This study is being conducted to compare biologic or metabolic activity of brain tumors in pediatric patients as determined by 1H-MRSI and [18F-]-FDG PET scanning and to correlate results of 1H-MRSI and 18F-FDG PET imaging with outcome. Patients undergo a 1H-MRSI and FDG PET within 1 week of each other. The study is ongoing and accrual of pediatric patients continues.We have enrolled approximately 15 of 24 patients to date. We are currently working on co-registration of FDG PET and 1H-MRSI data. Results are pending.